Speed responsive apparatus



1942- J. w. LIVINGSTON .-.-'rA 3 3 SPEED RESPONSIVE APPARATUS Filed Oct. 15, 1941 THEIR TTORNE'V Patented Dec. 22, 19 12 UNITED STATES- PATENT vo==c-- A V asossu smun aEsroNsvn APPABATUS John W. Llvlngton and Berberi, L. Bone, Forest Hills, Pa., assignors to The Union Switch & Signal Company, Swissvalc, Pa., a co'po'atlon of Pennylvania Our invention relates to speed responsive apparatus, and particularly to governors of the hydraulic type.

One of the simplest' forms of hydraulic governors consists of a pump of the gear or vane type arranged to pump fluid into a chamber having a fixed oriflce, the speed being determined by measuring the pressure of the fluid built up in the chamber. This type of governor is open to the disadvantage that the pressure of the fluid built up in the chamber is also a function of the viscosity of the fluid, and the governor is therefore not accurate unless the fluid is maintained at the same viscosity. In actual practice, it is difficult to maintain the fluid at the same vis'cosity since the governors are frequently subjected to, temperature changes between zero and 100 F., and this change in temperature causes a considerable change in viscosity of all ordinary fluids which are suitable !or use in a fluid governor.

Referring to the drawing, the reference characters PI and P! designate two similar fluid pumps which may be of any suitable type, but which are here illustrated 'as being of the well-known gear type. These pumps are disposed within a fluid tight housing i, and are arranged to be driven atthe same speed by a shaft 2 joumaled in bearings 3 and 4 provided in the top and bottom walls la and lb of the housing I. The upper end of the shaft 2 projects outside of the housing I, and is provided with a driving gear 22 by means of which the shaft may be driven at a speed which is proportional to the speed of One object of our present invention is the I fluid pump discharging fluid into a flrst chamber provided with a fixed oriflce and a variable oriflce. We also provide a second fluid pump operated at the same speed as the flrst pump and discharging fluid into a second chamber provided with two variable oriflces the opening in one of which is varied in response to variation in the pressure in the first chamber to maintain the pressure in the second chamber constant for a preselected viscosity of the fluid, and the opening in the other of which is varied in response to changes in pressure in the second chamber due to changes in vscosity of the fluid, whereby the opening of the second oriflce is a measure of the viscosity of the fluid. We further vary the opening of the variable oriflce in the first chamber in accordance with the opening of said other variable oriflce in the second chamber in a manner to compensate for changes in viscosity measured by means of the second chamber. We determine the speed by measuring the pressure built up in the first chamber.

Other objects and characteristic features of our invention will become apparent' as the description proceeds. i

Weshall describe one form of speed responsive apparatus embodying our invention, and shall then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showing one form of apparatus embodying our invention.

any device whose speed it is desired to have the governor respond to.

The housing l is partly filled with fluid 5 which may be oil, andthe pump PI pumps fluid from the bottom of the housing into a chamber 6. The chamber 6 is provided, with a flxed oriflce 'l and with a variable oriflce 8 the size of the opening of which is arranged to be varied by a needle vent valve 8. The chamber 6 is also provided with a movable diaphragm n and with a pipe ll which leads to a pressure responsive device, here shown as a Bourdon tube !2. The Bourdon tube l2 is provided'with a back contact l3-l3a which is closed when the pressure to which the tube |2 is subjected is below a prede: termined value and with a plurality of front contacts 3 3b, i3-l3c and I3-l3d which close successively as 'the pressure to which the tube !2 is subjected increases.

The pump PZ pumps fluid from the bottom of the housing l into a chamber |4 which is provided with a movable diaphragm |5, and with two variable oriflces 16 and s, the size of the openings of which may be varied by means of needle vent valves l'l and !9, respectively.

The diaphragm ll) in chamber 6 is biased to an upper position by means of a compressed coil spring 20, and is connected to the needle valve H in such manner that the area of the opening of the variable oriflce [6 is proportional to the pressure of the fluid in chamber 6.

The diaphragm l5 in chamber !4 is biased downwardly by a spring 2| and is connected to the needle valves 9 and s. All of the orifices discharge fluid into the housing l to enable it to be 'recirculated by the pumps PI and P2.

With the apparatus constructed in the manner described it will be apparent that when the pumps PI and P2 are operating the fluid which is discharged into the chambers 6 and |4 will tend' to build up pressures inthese chambers. The amount of the pressure which is built up in chamber 6 is determined primarily by the rate of discharge from oriflce 'l which is a fixed oriflce, and as this pressure increases the diaphragm o will deflect an amount which depends upon this pressure and the force exerted by spring 20.

the neede valve l'l in the direction to increase the area of the opening ot the variable oriflce I l. and the parts are so proportioned that tor some fixed assumed viscosity ot the fluid, the pressure -in chamber M will remain constant as the 'pressure in chamber I increases. It follows that the proportions ofneedle valve I 'I depend upon the relative discharge rates ol' pumps PI and PI, and the characteristics of spring 20, but not upon changes in the viscosity o! 'the fluid I.

When the viscosity oi' the fluid I increases, the pressure in chambers and M will both tend to increase due to the increase in viscosity. This increase in pressure in chamber M will deflect diaph-agm I! in opposition to the bias oi' spring :I and will cause neede valve s to increase the area of the opening of the variable oriflce lt until a point of equilibrium is reached. It follows that the area oi' the oriflce il will be a measure of the viscosity oi' the fluid 5, and that, since this area depends upon the amount ot motion ot this neede valve, the motion of this neede valve will also be a measure of the viscosity ol the fluid. Inasmuch as neede valve 9 is connected to neede valve s any movement of the neede valve !9 will be accompanied by a corresponding movement ot neede valve i, and this iatter valve is so designed that the resultant changes in the area of the opening of the variable oriflce 8 will compensate tor any variatio'ns in the pressure ot the fluid in chamber 6 which would occur due to changes in the viscosity of the fluid it this oriflce were not provided.

It will be seen, thereiore, that with a govemor constructed in accordance with our invention thepressure built up in chamber 6 will be independent ot changes in the viscosity o! the fluid,

and that themeasure ot thispressure by means.

oi' the Bourdon tube I! and associated contacts will be an accurate measu'e of the speed of the Although we have herein shown and described only one form of speed responsive apparatus embodying our invention. it is understood that various changes and modifications may be made therein within the scope or the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention. what we claim is:

1. A hydraulic govemor comprising a first fluid pump discharging fluid into a flrst chamber provided with a fixed oriflce, a variable orlflce and a diaphragm the displacement ot which is proportional to the pressure oi the fluid in said flrst chamber; a second fluid pump discharging fluid into a second chamber provided with two variable oriflces and with a diaphragm the displacement of which is proportional to the pressure of the fluid in said second chamber; means controlled by the diaphragm 'in said first chamber !or varying the opening oi'the one variable oriflce in said second chamber to hold the pressure in the second chamber constant at a selected viscosity oi' the fluid, means controlled by the diaphragm in the second chamber for varying the opening o! the other variable oriflce in said in the flrt chamber in ceordance with veristionsinthe opening otssidothervsriabeorlflee to compensate in the flrst chamber tor changes inthepressureduetochangesintheviscosiw ot'the fluid'measured by means ot the second chamber. x

2. Ahydraulic govemor comprisingaflrstfluid pumpdischargingfluid intoaflrstchamberprovided with a flxedoriflce, a variible oriflce and second chamber in such manner that the openi a diaph-agm the displacementt which i proportional to the pressure of the sum in said first 'chamber: a second fluid pump rling fluid into a second chamber provi with two variable oriflces and with a diaphrsgm the dispiaeement of which is proportional to' the presin-e ot the fluid in said second chamber; means centrolled by the diaphragm in saidflrst chamber !or varying the opening of the one variable oriflceinsaidsecondchambertoholdthepressue in the second chamber constant st` a selected viscosity oi the fluid, means ,controlled by the dlaphragm in the second chamber !or varying the opening ot the other variable oriflce in said second chamber in such manner that the opening of said other variable oriflce will be provoitional to the viscosity oi' the fluid, means to! varying the opening o! the variable orlflce in the flrst chamber in accordance with variations in the opening of said other variable oiflce to compensate in the flrst chamber !or changes in the pressure due to changes in the viscosity of the fluid measured by meine of the second chamber, and pressure responsive controlmeans controlled in accordance with the pressure in, said second chamber constant tor a predetermlned viscosity of the fluid, means responsive to s change in pressure in the second chamber due to a change in the viscoslty ot the fluid tor-controlling the'opening ot said variable oriflce to compensate tor changes in the pressure'in the 'flrst chamber due to changes in visoosity ot the fluid, and speed indication means responsive to the pressure in said first chamber.,

4. A hydraulic govemor comprising aflrst fluid pump discharging fluid into a flrst chamber provided with a fixed and a variable oriflce, means including a second fluid pump operated at the same speed as the first pump for discharging fluid into a second chamber, means responsive to the pressure ot the fluid in said flrst chamber i'or maintaining the pressure oi the fluid in said second chamber constant for a predete'mined viscosity of the fluid, means responsive to a change in pressure in the second chamber due to a change in the viscosity oi' the fluid tor controlling the opening oi' said variable oriflce to compensate tor changes in the pressure in the first chamber due to changes in viscosity of the fluid, and a Bourdon tube subjected to the pressure ot the fluid in said flrst chamber.

JOHN W. LIVINGSTON.

'I' L. BONI. 

